Most newly manufactured cellulose-containing fabrics have a handle that is rather hard and stiff unless they are treated with finishing components. In addition, the fabric surface appears not smooth due to small fuzzy fibers protruding from its surface. Furthermore, after a relatively short period of wear, pilling appears on the fabric surface, giving it an unappealing, worn look. For these reasons, improving fabric handle, appearance and pilling resistance is one of the main goals of the textile industry. However, only partial success has been achieved.
A high degree of fabric softness and smoothness can be obtained by using fine, i.e., low-denier, yarns in weaving. However, the resulting cost is high as the loom output decreases proportionately with the weft yarn diameter.
A less expensive way of ensuring a soft and smooth fabric handle is to impregnate the finished fabric with a softening agent, typically a cationic, sometimes silicone-based, surface active compound. However, this treatment does not remove pills and fuzz. Furthermore, the fabric obtains a somewhat greasy handle and is not wash-proof and its moisture absorbency is often considerably reduced.
One chemical method is crosslinking fibers to reduce the fibrillation (Nicolai et al, 1996, Textile Res. J. 66(9) 575-580). However, this method causes a decrease in fiber tenacity.
Another known method for obtaining a soft and smooth fabric is treating cellulosic fabrics with cellulases. See, Bazin et al., "Enzymatic Bio-Polishing of Cellulosic Fabric," presented at the 58th Congress of the Association of Chemists and the Textile Industry in Mulhouse, France (Oct. 25, 1991) and Asferg et al., "Softening and polishing of cotton fabrics by cellulase treatment," ITB Dyeing/Printing/Finishing (February 1990). Cellulase treatment of the fabric surface improves fabric quality with respect to handle, appearance and pilling resistance. The most important effects are less fuzz and pilling, increased gloss/luster, improved fabric handle, increased durable softness, and improved water absorbency. These effects are referred to as biopolishing effects. The particular conditions that are utilized are important in determining the outcome of the treatment.
Many processes require exposing the fabric to mechanical agitation to obtain satisfactory biopolishing results. See, for example, WO 9320278; Cavaco-Paulo et al. (1994, Biocatalysis 10:353-360); and Cavaco-Paulo et al. (1996, Textile Res. J. 66:287-294). However, under some conditions, significant weight loss and strength loss are also observed.
Current methods in cellulase biopolishing are mainly batch processes. The common continuous or semi-continuous processes such as pad-steamer/J-box are not used because they do not provide high mechanical action and use only small volumes of solution and thus result in insufficient and/or uneven biopolishing. For example, non-uniform biopolishing can result from the use of a cellulase complex, in part because different cellulases exhibit different affinities for cellulose and thus are differentially bound by the fabric.
Thus, there is a need in the art for effective biopolishing methods that can be used in conventional continuous or semi-continuous processes.